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Managing capacity automatically with Amazon RDS storage autoscaling - Amazon Relational Database Service
LimitationsEnabling storage autoscaling for a new DB instanceChanging the storage autoscaling settings for a DB instanceManually scaling your DB instance down or inTurning off storage autoscaling for a DB instanceAutoscaling for additional storage volumes
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Managing capacity automatically with Amazon RDS storage autoscaling

If your workload is unpredictable, you can enable storage autoscaling for an Amazon RDS DB instance. To do so, you can use the Amazon RDS console, the Amazon RDS API, or the Amazon CLI.

Note

For RDS for Oracle and RDS for SQL Server DB instances that use additional storage volumes, you can enable storage autoscaling for each additional storage volume independently, in addition to the primary storage volume. Each volume has its own maximum storage threshold. For more information, see Storage autoscaling for additional storage volumes.

For example, you might use this feature for a new mobile gaming application that users are adopting rapidly. In this case, a rapidly increasing workload might exceed the available database storage. To avoid having to manually scale up database storage, you can use Amazon RDS storage autoscaling.

With storage autoscaling enabled, when Amazon RDS detects that you are running out of free database space it automatically scales up your storage. Amazon RDS starts a storage modification for an autoscaling-enabled DB instance when these factors apply:

  • Free available space is less than or equal to 10 percent of the allocated storage.

  • The low-storage condition lasts at least five minutes.

  • Storage optimization has completed on the instance for the previous storage modification, and fewer than four storage modifications have occurred in the past 24 hours.

The additional storage is in increments of whichever of the following is greater:

  • 10 GiB

  • 10 percent of currently allocated storage

  • Predicted storage growth exceeding the current allocated storage size in the next 7 hours based on the FreeStorageSpace metrics from the past hour. For more information on metrics, see Monitoring with Amazon CloudWatch.

The maximum storage threshold is the limit that you set for autoscaling the DB instance. It has the following constraints:

  • You must set the maximum storage threshold to at least 10% more than the current allocated storage. We recommend setting it to at least 26% more to avoid receiving an event notification that the storage size is approaching the maximum storage threshold.

    For example, if you have DB instance with 1000 GiB of allocated storage, then set the maximum storage threshold to at least 1100 GiB. If you don't, you get an error such as Invalid max storage size for engine_name. However, we recommend that you set the maximum storage threshold to at least 1260 GiB to avoid the event notification.

  • For a DB instance that uses Provisioned IOPS (io1 or io2 Block Express) storage, the ratio of IOPS to maximum storage threshold (in GiB) must be within a certain range. For more information, see Provisioned IOPS SSD storage.

  • You can't set the maximum storage threshold for autoscaling-enabled instances to a value greater than the maximum allocated storage for the database engine and DB instance class.

    For example, SQL Server Standard Edition on db.m5.xlarge has a default allocated storage for the instance of 20 GiB (the minimum) and a maximum allocated storage of 16,384 GiB. The default maximum storage threshold for autoscaling is 1,000 GiB. If you use this default, the instance doesn't autoscale above 1,000 GiB. This is true even though the maximum allocated storage for the instance is 16,384 GiB.

Note

We recommend that you carefully choose the maximum storage threshold based on usage patterns and customer needs. If there are any aberrations in the usage patterns, the maximum storage threshold can prevent scaling storage to an unexpectedly high value when autoscaling predicts a very high threshold. After a DB instance has been autoscaled, its allocated storage can't be reduced.

Limitations of storage autoscaling

The following limitations apply to storage autoscaling:

  • Autoscaling doesn't occur if the maximum storage threshold would be exceeded by the storage increment.

  • When autoscaling, RDS predicts the storage size for subsequent autoscaling operations. If a subsequent operation is predicted to exceed the maximum storage threshold, then RDS autoscales to the maximum storage threshold.

  • Autoscaling can't completely prevent storage-full situations for large data loads. This is because further storage modifications can't be made until storage optimization completes on the instance, and are limited to a maximum of four modifications within any 24-hour period.

    If you perform a large data load, and autoscaling doesn't provide enough space, the database might remain in the storage-full state for several hours. This can harm the database.

  • If you start a storage scaling operation at the same time that Amazon RDS starts an autoscaling operation, your storage modification takes precedence. The autoscaling operation is canceled.

  • Autoscaling can't decrease the allocated storage. You can't reduce the amount of storage for a DB instance after storage has been allocated.

  • Autoscaling can't be used with magnetic storage.

  • Autoscaling can't be used with the following previous-generation instance classes that have less than 6 TiB of orderable storage: db.m3.large, db.m3.xlarge, and db.m3.2xlarge.

  • Autoscaling operations aren't logged by Amazon CloudTrail. For more information on CloudTrail, see Monitoring Amazon RDS API calls in Amazon CloudTrail.

  • For additional storage volumes on RDS for Oracle and RDS for SQL Server DB instances, autoscaling is evaluated independently for each volume against that volume's own maximum storage threshold. The preceding limitations apply to each additional storage volume in the same way that they apply to the primary volume. For more information about additional storage volumes, see Adding storage volumes.

Although automatic scaling helps you to increase storage on your Amazon RDS DB instance dynamically, you should still configure the initial storage for your DB instance to an appropriate size for your typical workload.

Enabling storage autoscaling for a new DB instance

When you create a new Amazon RDS DB instance, you can choose whether to enable storage autoscaling. You can also set an upper limit on the storage that Amazon RDS can allocate for the DB instance.

Enabling storage autoscaling doesn't require a database reboot and doesn't cause any downtime. The feature takes effect immediately without disrupting database operations.

Note

When you clone an Amazon RDS DB instance that has storage autoscaling enabled, that setting isn't automatically inherited by the cloned instance. The new DB instance has the same amount of allocated storage as the original instance. You can turn storage autoscaling on again for the new instance if the cloned instance continues to increase its storage requirements.

To enable storage autoscaling for a new DB instance

  1. Sign in to the Amazon Web Services Management Console and open the Amazon RDS console at https://console.amazonaws.cn/rds/.

  2. In the Amazon RDS console, choose the Amazon Region where you want to create the DB instance.

  3. In the navigation pane, choose Databases.

  4. Choose Create database. On the Select engine page, choose your database engine and specify your DB instance information as described in Getting started with Amazon RDS.

  5. In the Storage autoscaling section, set the Maximum storage threshold value for the DB instance.

  6. Specify the rest of your DB instance information as described in Getting started with Amazon RDS.

To enable storage autoscaling for a new DB instance, use the Amazon CLI command create-db-instance. Set the following parameter:

  • --max-allocated-storage – Turns on storage autoscaling and sets the upper limit on storage size, in gibibytes.

To verify that Amazon RDS storage autoscaling is available for your DB instance, use the Amazon CLI describe-valid-db-instance-modifications command. To check based on the instance class before creating an instance, use the describe-orderable-db-instance-options command. Check the following field in the return value:

  • SupportsStorageAutoscaling – Indicates whether the DB instance or instance class supports storage autoscaling.

For more information about storage, see Amazon RDS DB instance storage.

To enable storage autoscaling for a new DB instance, use the Amazon RDS API operation CreateDBInstance. Set the following parameter:

  • MaxAllocatedStorage – Turns on Amazon RDS storage autoscaling and sets the upper limit on storage size, in gibibytes.

To verify that Amazon RDS storage autoscaling is available for your DB instance, use the Amazon RDS API DescribeValidDbInstanceModifications operation for an existing instance, or the DescribeOrderableDBInstanceOptions operation before creating an instance. Check the following field in the return value:

  • SupportsStorageAutoscaling – Indicates whether the DB instance supports storage autoscaling.

For more information about storage, see Amazon RDS DB instance storage.

Changing the storage autoscaling settings for a DB instance

You can turn storage autoscaling on for an existing Amazon RDS DB instance. You can also change the upper limit on the storage that Amazon RDS can allocate for the DB instance.

Changing storage autoscaling settings doesn't require a database reboot and doesn't cause any downtime. The changes take effect immediately without disrupting database operations.

To change the storage autoscaling settings for a DB instance

  1. Sign in to the Amazon Web Services Management Console and open the Amazon RDS console at https://console.amazonaws.cn/rds/.

  2. In the navigation pane, choose Databases.

  3. Choose the DB instance that you want to modify, and choose Modify. The Modify DB instance page appears.

  4. Change the storage limit in the Autoscaling section. For more information, see Modifying an Amazon RDS DB instance.

  5. When all the changes are as you want them, choose Continue and check your modifications.

  6. On the confirmation page, review your changes. If they're correct, choose Modify DB instance to save your changes. If they aren't correct, choose Back to edit your changes or Cancel to cancel your changes.

    Changing the storage autoscaling limit occurs immediately. This setting ignores the Apply immediately setting.

To change the storage autoscaling settings for a DB instance, use the Amazon CLI command modify-db-instance. Set the following parameter:

  • --max-allocated-storage – Sets the upper limit on storage size, in gibibytes. If the value is greater than the --allocated-storage parameter, storage autoscaling is turned on. If the value is the same as the --allocated-storage parameter, storage autoscaling is turned off.

To verify that Amazon RDS storage autoscaling is available for your DB instance, use the Amazon CLI describe-valid-db-instance-modifications command. To check based on the instance class before creating an instance, use the describe-orderable-db-instance-options command. Check the following field in the return value:

  • SupportsStorageAutoscaling – Indicates whether the DB instance supports storage autoscaling.

For more information about storage, see Amazon RDS DB instance storage.

To change the storage autoscaling settings for a DB instance, use the Amazon RDS API operation ModifyDBInstance. Set the following parameter:

  • MaxAllocatedStorage – Sets the upper limit on storage size, in gibibytes.

To verify that Amazon RDS storage autoscaling is available for your DB instance, use the Amazon RDS API DescribeValidDbInstanceModifications operation for an existing instance, or the DescribeOrderableDBInstanceOptions operation before creating an instance. Check the following field in the return value:

  • SupportsStorageAutoscaling – Indicates whether the DB instance supports storage autoscaling.

For more information about storage, see Amazon RDS DB instance storage.

Manually scaling your DB instance down or in

Amazon RDS provides storage autoscaling to meet growing demand. However, there are limitations regarding scaling down and in:

  • RDS storage – While RDS supports automatic scaling up of storage as demand increases, it doesn't automatically scale down.

  • Read replicas – RDS doesn't support automatic scaling out (adding) or scaling in (deleting) of read replicas. You must manually add or remove read replicas according to your load requirements.

To scale down your RDS resources, perform the following manual actions:

  • For storage, you can't manually reduce the allocated storage of a DB instance using the modify-db-instance command. Instead, choose one of the following techniques:

    • Use a blue/green deployment if your DB engine supports it. Create a green database with a lower storage size, and then promote your green database to be your blue database. For more information, see Modify storage and performance settings.

    • Create a new DB instance with lower allocated storage, manually migrate the data from your current database to the newly created database instance, and switch your database endpoints.

  • For read replicas, manually delete any unused replicas through the RDS console or Amazon CLI.

Turning off storage autoscaling for a DB instance

If you no longer need Amazon RDS to automatically increase the storage for an Amazon RDS DB instance, you can turn off storage autoscaling. After you do, you can still manually increase the amount of storage for your DB instance.

To turn off storage autoscaling for a DB instance

  1. Sign in to the Amazon Web Services Management Console and open the Amazon RDS console at https://console.amazonaws.cn/rds/.

  2. In the navigation pane, choose Databases.

  3. Choose the DB instance that you want to modify and choose Modify. The Modify DB instance page appears.

  4. Clear the Enable storage autoscaling check box in the Storage autoscaling section. For more information, see Modifying an Amazon RDS DB instance.

  5. When all the changes are as you want them, choose Continue and check the modifications.

  6. On the confirmation page, review your changes. If they're correct, choose Modify DB instance to save your changes. If they aren't correct, choose Back to edit your changes or Cancel to cancel your changes.

Changing the storage autoscaling limit occurs immediately. This setting ignores the Apply immediately setting.

To turn off storage autoscaling for a DB instance, use the Amazon CLI command modify-db-instance and the following parameter:

  • --max-allocated-storage – Specify a value equal to the --allocated-storage setting to prevent further Amazon RDS storage autoscaling for the specified DB instance.

For more information about storage, see Amazon RDS DB instance storage.

To turn off storage autoscaling for a DB instance, use the Amazon RDS API operation ModifyDBInstance. Set the following parameter:

  • MaxAllocatedStorage – Specify a value equal to the AllocatedStorage setting to prevent further Amazon RDS storage autoscaling for the specified DB instance.

For more information about storage, see Amazon RDS DB instance storage.

Storage autoscaling for additional storage volumes

For RDS for Oracle and RDS for SQL Server DB instances that use additional storage volumes, you can enable storage autoscaling for each additional storage volume independently, in the same way that you enable it for the primary storage volume. Each volume – the primary volume and each additional storage volume – has its own maximum storage threshold, and Amazon RDS evaluates and scales each volume independently against that threshold. For more information about additional storage volumes, see Adding storage volumes.

The conditions that trigger autoscaling, the storage increment that Amazon RDS adds, and the constraints on the maximum storage threshold are the same for an additional storage volume as they are for the primary volume. For a description of these conditions and constraints, see Managing capacity automatically with Amazon RDS storage autoscaling. The limitations in Limitations of storage autoscaling also apply to each additional storage volume.

Amazon RDS validates the maximum storage threshold for each additional storage volume independently, against the storage settings of that volume. For a volume that uses Provisioned IOPS (io1 or io2 Block Express) or gp3 storage, the ratio of IOPS to the volume's maximum storage threshold (in GiB) must be within the same range that applies to the volume's allocated storage. For these ranges, see Provisioned IOPS SSD storage.

When Amazon RDS autoscales an additional storage volume, it emits events that identify the affected volume. Amazon RDS emits RDS-EVENT-0541 and RDS-EVENT-0542 when it begins and finishes an autoscaling-initiated modification, and RDS-EVENT-0594, RDS-EVENT-0595, and RDS-EVENT-0593 when a volume reaches or approaches its maximum storage threshold, or when autoscaling can't scale the volume. To avoid the approaching-threshold notification, set the maximum storage threshold for each volume to at least 26 percent more than its allocated storage. For more information, see Amazon RDS event categories and event messages .

You set the maximum storage threshold for an additional storage volume in the same dialog that you use to add or modify the volume. When you add or modify an additional storage volume, set the Maximum storage threshold for that volume to turn on storage autoscaling for it. For the full procedure to add or modify an additional storage volume, see Adding storage volumes.

To enable storage autoscaling for an additional storage volume, use the Amazon CLI command modify-db-instance and set the MaxAllocatedStorage field for the volume within the --additional-storage-volumes JSON array. The value sets the upper limit on storage size for that volume, in gibibytes. If the value is greater than the volume's AllocatedStorage, storage autoscaling is turned on for the volume. If the value is the same as the volume's AllocatedStorage, storage autoscaling is turned off for the volume.

The following example turns on storage autoscaling for the additional storage volume named rdsdbdata2 by setting its maximum storage threshold to 10,000 GiB.

aws rds modify-db-instance \
    --db-instance-identifier mydbinstance \
    --additional-storage-volumes '[
        {
            "VolumeName": "rdsdbdata2",
            "StorageType": "gp3",
            "AllocatedStorage": 5000,
            "MaxAllocatedStorage": 10000
        }
    ]'

To enable storage autoscaling for an additional storage volume, use the Amazon RDS API operation ModifyDBInstance and set the MaxAllocatedStorage field on the volume's entry in the AdditionalStorageVolumes array. This value sets the upper limit on storage size for that volume, in gibibytes. Set it to a value greater than the volume's AllocatedStorage to turn on storage autoscaling, or equal to AllocatedStorage to turn it off.